Scattering of Magnetic Mirror-trapped fast Electrons by an Alfv\'{e}n Wave

Highly energetic electrons produced naturally or artificially can be trapped in the earth's radiation belts for months, posing a danger to satellites. A technique for artificially de-trapping these electrons is under investigation at the Large Plasma Device (LaPD) at UCLA. The experiment is performed in a quiescent afterglow plasma ($n_e =0.1-1\times 10^{18}/m^3$, $T_e \approx 0.5eV$, $B_0 =400-1600G$, $L=18m$, and $diameter=0.6m)$. A population of runaway electrons is generated by 2$^{nd}$ harmonic ECRH (P=25kW, $\tau $=10-50ms, f=2.45GHz), as evidenced by production of X-rays with energy up to 5MeV. The fast electrons are trapped in a magnetic mirror field (R$_{m}$=1.1-4). A shear Alfv\'{e}n wave ($f$=110-230 kHz, $B_{wave}$=2G) is launched with a rotating magnetic field antenna. The Alfv\'{e}n wave is observed to dramatically affect the trapped fast electrons and scatter them out of the mirror.